This application is based on Application No. 2000-310458, filed in Japan on Oct. 11, 2000, the contents of which are hereby incorporated by reference.
The present invention relates to an occupant protecting apparatus such as an air bag system used for protecting an occupant at the time of collision of an automobile.
An air bag immediately expands between an occupant and a steering wheel or a dashboard at the time of collision of an automobile to protect the occupant. However, when a distance between the occupant and the steering wheel or the dashboard, for example, when the driver is small and driving the automobile near the steering wheel, or when a child is standing in front of a passenger seat, it is known that deployment of the air bag may damage the occupant in some cases. Further, when the occupant sitting on the passenger seat is a child younger than seven years old, even if the child is sitting on a normal position, it is safer not to deploy the air bag. For this reason, the United State is going to legislate to provide an occupant detecting apparatus in an occupant protecting apparatus using an air bag.
As the occupant protecting apparatus providing with the occupant detecting apparatus, there is a known apparatus described in Japanese Patent Application Laid-open No.H10-100858. A structure of this apparatus will be explained based on FIG. 6. In FIG. 6, a reference number 1 represents a front window shield 1. A front collision air bag 3 is accommodated in a dashboard 2 provided below the front window shield 1 such as to be opposed to a passenger seat 4. A reference number 5 represents a danger region where the occupant may be injured if the air bag 3 deploys. The dashboard 2 is provided with infrared beam emitting means 11 for emitting infrared beam and infrared beam detecting means 16 having a PSD. The infrared beam emitting means 11 and the infrared beam detecting means 16 constitute position detecting means 20.
Next, operation of this conventional occupant protecting apparatus will be explained. As shown in FIG. 6, infrared beam is emitted diagonally upward from the infrared beam emitting means 11. When there is no person in the danger region 5, e.g., when an adult person is sitting on the passenger seat 4 normally, the infrared beam reaches a ceiling 6 in the occupant room, and an infrared beam spot is made on the ceiling 6. On the contrary, when a person exists in the danger region 5, e.g., when a child stands up in front of the passenger seat 4, since the infrared beam is blocked by the person, the infrared beam spot is made on the person""s body. By detecting the position of the infrared beam spot using the infrared beam detecting means 16, a distance between the infrared beam detecting means 16 (i.e., dashboard 2) and the person""s body based on the principle of triangulation. When an electronic control unit (ECU) that is not shown judges that the detected distance is extremely small and it is danger to deploy the air bag 3 or when a collision is detected by an acceleration sensor, the air bag 3 is not opened to prevent the occupant from being injured by the air bag 3.
As examples of an occupant protecting apparatus having position detecting means for detecting a distance between a dashboard and a person""s body, there are a known apparatus using ultrasound as described in Japanese Patent Application Laid-open No.H11-286256, and a known apparatus using an optical sensor as described in Japanese Patent Application Laid-open No.H11-217056. However, in any of the apparatuses, the position detecting means is provided on the dashboard in front of the occupant or on a front end of a ceiling, and the distance between the dashboard and a front surface of the occupant. Therefore, when the occupant opens a magazine or newspaper, or when the occupant expands his or her hand forward, the system erroneously recognizes that a person exists in the danger region, and there is a problem that the air bag is prevented from opening even when the automobile collides and it is necessary to open the air bag.
Further, the occupant is not always in the normal position, and he or she may be sitting on a laterally deviated position. Therefore, with the method using one infrared beam as in the conventional technique, infrared beam is not emitted to the person""s body in some cases.
Further, there is a known method for detecting motion of an occupant at the time of collision by means of the position detecting means to detect the collision, thereby controlling the operation of the occupant protecting apparatus such as an air bag as described in U.S. Pat. No. 5,118,134. However, response sensitivity of a distance sensor and disturbance resistance are not practically sufficient, and this method has not yet been in the actual use. For example, in the case of the distance sensor using ultrasound, the velocity of sound is limited. Therefore, in order to detect a distance of 1 m for example, a response speed can not be faster than 6 ms that is required for sound to reciprocate through 1 m in principle. A position detecting means using the PSD also has a problem that the response speed can not be made faster if normal operation of the position detecting means is secured even when strong disturbance light is applied to the occupant such as direct sunlight.
Further, there is a problem that if not only the longitudinal collision, but also a lateral collision is also to be detected by the position detecting means, another position detecting means for detecting the lateral position is separately required.
The present invention has been accomplished to solve the above problems, and it is an object of the invention to provide an occupant protecting apparatus capable of safely controlling the operation method with a simple structure.
An occupant protecting apparatus of the present invention comprises infrared beam emitting means disposed on an upper portion of an occupant room of a vehicle at a position diagonally rearward of a position of a passenger seat for emitting infrared beam, infrared beam detecting means disposed on a position offset from the infrared beam emitting means for detecting a position of a light spot generated in such a manner that flat infrared beam impinges an occupant on a seat and scatters, and control means for obtaining a size of the occupant or a three-dimensional shape of sitting position or the like from output of the infrared beam detecting means to control motion of a protecting apparatus such as an air bag.
Infrared beam is emitted using the infrared beam detecting means from a direction diagonally rearward of the position of the occupant""s head sitting on the seat, thereby detecting a physique of the occupant or a three-dimensional shape of the sitting position by means of the infrared beam detecting means. Based on the detected result, the operation of the protecting apparatus such as the air bag is controlled by the control means, thereby obtaining a safe occupant protecting apparatus.
The infrared beam emitting means is disposed on a ceiling of the vehicle in the vicinity of a room lamp diagonally rearward of a position of a head of an occupant on a driver""s seat or a passenger seat.
The infrared beam emitting means emits flat infrared beam sheet, a set of a plurality of infrared beams arranged in a form of a sheet or infrared beam that scans in a form of a sheet.
The infrared beam detecting means comprises a two-dimensional image sensor disposed on a position offset from the infrared beam emitting means in order to detect the position of the light spot generated in such a manner that the infrared beam sheet or beam impinges the occupant on the seat and scatters.
The infrared beam emitting means includes an anamorphic optical system.
The control means judges whether the occupant is an adult or a child from the size of the head of the occupant detected by the infrared beam detecting means.
The control means judges whether an object is a stationary object such as a child seat from presence or absence of motion of the light spot on the object.
The infrared beam emitting means can emit flat infrared beam sheet, a set of a plurality of infrared beams arranged in a form of a sheet or infrared beam that scans in a form of a sheet to a plurality of vertical positions.
The infrared beam detecting means includes an image sensor having a frame rate of 200 fps or greater in order to detect the position of the light spot generated in such a manner that the infrared beam sheet or beam impinges the occupant on the seat and scatters.
The infrared beam detecting means comprises a two-dimensional CMOS image sensor having a projection function.
The two-dimensional CMOS image sensor functions as a one-dimensional image sensor using the projection function when acceleration of the vehicle exceeds a predetermined value.
The control means detects a collision state from longitudinal motion of the occupant detected by the infrared beam detecting means at an instant when a front collision of the vehicle occurs.
The control means detects a collision state from lateral motion of the occupant detected by the infrared beam detecting means at an instant when a side collision of the vehicle occurs.